Alcohol usage over time results in a number of metabolic alterations to several organ systems including changes in liver function. One of the latter changes is the production and secretion into the blood of an isoform of the transferrin molecule. The pI 5.7 transferrin isoform can be detected by isoelectric focusing and its quantities have been shown to directly correlate with the amount of alcohol intake by an individual over a time period related to the turnover rate of transferrin in blood. The pI 5.7 transferrin isoform diminishes back to normal levels after alcohol intake is stopped. The literature shows that quantitation of the 5.7 transferrin isoform is clinically useful for initial estimation of alcohol usage and for monitoring individuals under treatment for alcoholism disease. Present tests for the 5.7 transferrin are time-consuming, require a technical expertise usually not available in clinical laboratories and are expensive to perform. The purpose of this proposal is to delineate the molecular difference between the native (pI 5.4) and the pI 5.7 transferrin isoform. The approach and methodology for determining this difference is explained in the text. Based upon the molecular difference(s) we will construct an immunoassay that can be used directly on serum or plasma specimens to quantitate the pI 5.7 transferrin form. The assay will be similar to other immunoassay tests for blood proteins, cost effective, and thus we trust will find wider usage in the clinical management of alcoholism.